The present invention relates to high speed switching circuits.
Many circuits have been proposed heretofore for providing an output signal which switches from one state to another, depending on the relative values of two input signals, or an input signal and a reference against which it is to be compared. More specifically, a number of related prior patents include U.S. Pat. No. 3,054,910 granted Sept. 18, 1962; U.S. Pat. No. 3,671,767 granted June 20, 1972; U.S. Pat. No. 3,848,139 granted Nov. 12, 1974; and U.S. Pat. No. 3,988,595 granted Oct. 26, 1976.
Although the foregoing circuits are similar in certain respects, and some include positive feedback to increase the speed of transition, the circuits in general are not fully compatible with present day integrated circuit technology, and specifically with Integrated Injection Logic, known as I.sup.2 L, or with Transistor-Transistor Logic, known as T.sup.2 L.
Accordingly, an important object of the present invention is to provide a comparator circuit which is fully compatible with integrated circuitry, both of the I.sup.2 L and the T.sup.2 L types. Collateral objects of the invention are to obtain a high speed transition substantially independent of the amount of overdrive, and to avoid comparator circuit oscillation.